Joining polyhedral objects using implicitly defined surfaces

Complex polyhedral objects are often constructed from simpler polyhedral ob jects using constructive solid geometry, booleans, skinning and shrinkwrap techniques. This paper presents a new technique for incrementally building complex polyhedral objects from simpler polyhedral parts. We provide a proc edural implicit function definition for a region of a polyhedral object tha t is star-shaped with respect to a skeletal point, called a blend center. W e extend this definition to provide a single implicit function definition f or an arbitrary polyhedral object, where every region is star-shaped with r espect to a proximal blend center, chosen from an arbitrary set of blend ce nters. This allows the application of implicit function-based modeling tech niques in constructing transition surfaces between arbitrary polyhedral obj ect parts. At the same time the original detail and character of object par ts are preserved in regions where they do not blend or interact with other object parts. A complete implementation of the concepts presented shows pol yhedral implicit primitives to be an efficient and general technique for bu ilding complex polyhedral objects from a modular set of polyhedral object p arts.